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Mäkinen S, Datta N, Rangarajan S, Nguyen YH, Olkkonen VM, Latva-Rasku A, Nuutila P, Laakso M, Koistinen HA. Finnish-specific AKT2 gene variant leads to impaired insulin signalling in myotubes. J Mol Endocrinol 2023; 70:JME-21-0285. [PMID: 36409629 PMCID: PMC9874976 DOI: 10.1530/jme-21-0285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/21/2022] [Indexed: 11/22/2022]
Abstract
Finnish-specific gene variant p.P50T/AKT2 (minor allele frequency (MAF) = 1.1%) is associated with insulin resistance and increased predisposition to type 2 diabetes. Here, we have investigated in vitro the impact of the gene variant on glucose metabolism and intracellular signalling in human primary skeletal muscle cells, which were established from 14 male p.P50T/AKT2 variant carriers and 14 controls. Insulin-stimulated glucose uptake and glucose incorporation into glycogen were detected with 2-[1,2-3H]-deoxy-D-glucose and D-[14C]-glucose, respectively, and the rate of glycolysis was measured with a Seahorse XFe96 analyzer. Insulin signalling was investigated with Western blotting. The binding of variant and control AKT2-PH domains to phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) was assayed using PIP StripsTM Membranes. Protein tyrosine kinase and serine-threonine kinase assays were performed using the PamGene® kinome profiling system. Insulin-stimulated glucose uptake and glycogen synthesis in myotubes in vitro were not significantly affected by the genotype. However, the insulin-stimulated glycolytic rate was impaired in variant myotubes. Western blot analysis showed that insulin-stimulated phosphorylation of AKT-Thr308, AS160-Thr642 and GSK3β-Ser9 was reduced in variant myotubes compared to controls. The binding of variant AKT2-PH domain to PI(3,4,5)P3 was reduced as compared to the control protein. PamGene® kinome profiling revealed multiple differentially phosphorylated kinase substrates, e.g. calmodulin, between the genotypes. Further in silico upstream kinase analysis predicted a large-scale impairment in activities of kinases participating, for example, in intracellular signal transduction, protein translation and cell cycle events. In conclusion, myotubes from p.P50T/AKT2 variant carriers show multiple signalling alterations which may contribute to predisposition to insulin resistance and T2D in the carriers of this signalling variant.
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Affiliation(s)
- Selina Mäkinen
- Minerva Foundation Institute for Medical Research, Tukholmankatu, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Haartmaninkatu, Helsinki, Finland
| | - Neeta Datta
- Minerva Foundation Institute for Medical Research, Tukholmankatu, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Haartmaninkatu, Helsinki, Finland
| | - Savithri Rangarajan
- Pam Gene International B.V., Wolvenhoek, BJ ´s-Hertogenbosch, The Netherlands
| | - Yen H Nguyen
- Minerva Foundation Institute for Medical Research, Tukholmankatu, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Haartmaninkatu, Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Tukholmankatu, Helsinki, Finland
- Department of Anatomy, Faculty of Medicine, Haartmaninkatu, University of Helsinki, Helsinki, Finland
| | - Aino Latva-Rasku
- Turku PET Centre, University of Turku, Kiinamyllynkatu, Turku, Finland
- Turku PET Centre, Turku University Hospital, Kiinamyllynkatu, Turku, Finland
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Kiinamyllynkatu, Turku, Finland
- Turku PET Centre, Turku University Hospital, Kiinamyllynkatu, Turku, Finland
| | - Markku Laakso
- Institute of Clinical Medicine, Internal Medicine, University of Eastern Finland and Kuopio University Hospital, Puijonlaaksontie, Kuopio, Finland
| | - Heikki A Koistinen
- Minerva Foundation Institute for Medical Research, Tukholmankatu, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Haartmaninkatu, Helsinki, Finland
- Correspondence should be addressed to H A Koistinen:
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Zacharewicz E, Kalanon M, Murphy RM, Russell AP, Lamon S. MicroRNA-99b-5p downregulates protein synthesis in human primary myotubes. Am J Physiol Cell Physiol 2020; 319:C432-C440. [PMID: 32608991 DOI: 10.1152/ajpcell.00172.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
microRNAs (miRNAs) are important regulators of cellular homeostasis and exert their effect by directly controlling protein expression. We have previously reported an age-dependent negative association between microRNA-99b (miR-99b-5p) expression and muscle protein synthesis in human muscle in vivo. Here we investigated the role of miR-99b-5p as a potential negative regulator of protein synthesis via inhibition of mammalian target for rapamycin (MTOR) signaling in human primary myocytes. Overexpressing miR-99b-5p in human primary myotubes from young and old subjects significantly decreased protein synthesis with no effect of donor age. A binding interaction between miR-99b-5p and its putative binding site within the MTOR 3'-untranslated region (UTR) was confirmed in C2C12 myoblasts. The observed decline in protein synthesis was, however, not associated with a suppression of the MTOR protein but of its regulatory associated protein of mTOR complex 1 (RPTOR). These results demonstrate that modulating the expression levels of a miRNA can regulate protein synthesis in human muscle cells and provide a potential mechanism for muscle wasting in vivo.
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Affiliation(s)
- Evelyn Zacharewicz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Ming Kalanon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Robyn M Murphy
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - Aaron P Russell
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Séverine Lamon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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Zhao Z, Yu X, Jia J, Yang G, Sun C, Li W. miR-181b-5p May Regulate Muscle Growth in Tilapia by Targeting Myostatin b. Front Endocrinol (Lausanne) 2019; 10:812. [PMID: 31849840 PMCID: PMC6902659 DOI: 10.3389/fendo.2019.00812] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/06/2019] [Indexed: 12/20/2022] Open
Abstract
Background: Myostatin (Mstn), a member of the TGF-β superfamily, is a negative regulator of skeletal muscle mass in mammals. Precise regulation of Mstn expression is important for somite growth in fish. MicroRNA (miRNA), a type of small non-coding RNA, regulates gene expression at the post-transcriptional level and participates in various physiological functions. A growing amount of evidence has emphasized the importance of miRNA in the development of skeletal muscle. Aims: This study aims to study how miRNAs regulate myostatin b (mstnb) post-transcriptionally in tilapia. Methods/Results: Mstnb 3' UTR sequences were obtained, and the results of tissue distribution showed that mstnb was expressed in several tissues, including brain, white muscle, gut, and adipose tissue. A total of 1,992 miRNAs were predicted to target mstnb in tilapia using bioinformatics, and a dual-luciferase reporter experiment confirmed that miR-181a/b-5p, miR-30-3p, miR-200a, and miR-27a were the target miRNAs of mstnb. Mutagenesis of the miR-181b-5p binding sites of mstnb significantly increased the luciferase signal compared to the wild-type mstnb. In tilapia primary muscle cells, overexpression of miR-181b-5p led to the downregulation of MSTNb expression, and the inhibitory effect of MSTNb on the downstream genes was dismissed, while inhibition of miR-181b-5p could reverse these phenomena. Conclusion: Taken together, our results suggested that miR-181b-5p could promote the growth of skeletal muscle by decreasing the MSTNb protein level in tilapia.
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